Circuit components have been attached to PCB's typically by insertion of leads of the circuit component into plated-through holes in the PCB and then soldering the component in place. In production, one technique for attachment and soldering is known as wave soldering. In large scale wave soldering, electrical components are typically mounted to associate plated-through holes in the PCB, i.e., the leads of each of the electrical components are inserted through associated plated-through holes in the PCB. Certain sections of the PCB are masked with a protective coating to prevent solder from bridging between areas that should not be electrically connected together. The populated PCB is then passed across a molten solder bed having surface waves such that the solder comes in contact with, binds to, and mechanically secures the leads of the electrical components while also electrically connecting the leads of the electrical components to the circuit traces on the PCB.
High density electronics are often attached to PCBs using surface mount technology (“SMT”) instead of the older through-lead technology. Wave soldering can be used for surface mounted components, but frequently reflow soldering is instead used. Reflow soldering processes begin with the circuit components adhered to connection pads on the PCB with a solder paste. The populated PCB is then heated to melt (reflow) the solder to make the final electrical connection.
While the known soldering techniques have proven to be useful and reliable, each technique requires special equipment to accomplish the needed physical and electrical connections.